1. Field of the Invention
This invention relates to a robot control unit with which a user can easily make teaching data for a robot body having a plurality of joints.
2. Description of the Related Art
A typical conventional prior art is shown in FIG. 10. A robot body 110 having a plurality of joints is connected to a robot control unit 120 through a electric signal line 111. A teach-inputting means 130, which is called a teaching pendant or the like, is connected to the robot control unit 120 through a bendable electric signal line 121. By operating the teach-inputting means 130, teaching data for positions of the plurality of joints are inputted, while the robot body 110 actually moves. The inputted teaching data are replayed by the robot control unit 120 to drive each of the joints of the robot body 110. The control unit 120 may have displaying means 122 such as a cathode-ray tube screen, for displaying the inputted teaching data and information of moving states of the robot body 110.
The robot control unit 120 may have a choosing switch 140. As shown in FIG. 10A, the choosing switch 140 has a knob 141, which an operator turns for choosing one from teaching operation mode by the teach-inputting means 130 and replaying operation mode for the robot body 110 using the teaching data.
FIG. 11 is a block diagram showing a electrical structure of the prior art shown in FIG. 10. The robot control unit 120 is constructed in such a manner that processing means 150 and a servo unit 160 are accommodated in one housing.
FIG. 12 a flow chart for explaining a general operation of the prior art shown in FIGS. 10 and 11. As shown in the FIG. 12, at a step a1, a power supply is given to the robot control unit, and the teaching operation mode where a teaching operation can be executed is chosen by turning the knob 141 of the choosing switch 140. The choosing switch 140 is connected to a processing circuit 151 which can be materialized by a microcomputer in the processing means 150. The replaying operation for the robot body 110 is prohibited in a step a2.
At a step a3, a key-input panel 131 of the teach-inputting means 130 is operated. Then, the operation is detected by a processing circuit 132 of a microcomputer. Then, information about the teaching data is displayed by the displaying means 133 which can be materialized by a liquid crystal screen, and is temporarily stored in a memory 134. Then, the information is stored in a memory 152 in the processing means 150 through a line 121. Operating data of the processing circuit 151 are stored in a read-only-memory 153. Following the inputted teaching data, a processing circuit 161 of a microcomputer in a servo unit 160 executes programs stored in a read-only-memory 162 to temporarily store the teaching data in a memory 163. Thus, a driver 164 is controlled so that the positions of the joints are consistent with the inputted positions. A power output circuit 165 drives a motor 112 in the robot body 110 through a electric signal line 111. The positions of the joints are detected by encoders 113 and transmitted to the processing circuit 161, so that the joints are driven following the teach-inputting operation. During the teach-inputting operation, the robot body 110 actually moves and the operator can confirm the moving state of the robot body 110 by his eyes.
At a step a4, the operator confirms completion of the teach-inputting operation. At a step a5, the replaying operation mode where the replaying operation can be executed is chosen by turning the knob 141 of the choosing switch 140. Thus, the processing circuit 151 in the processing means 150 reads out the teaching data from the memory for teaching data 152. Then, the servo unit 160 operates the robot body 110 at a step a6.
Teaching data can be made by a personal computer at a remote place from which the operator can not see the robot body. A storage device such as a floppy disk storing the teaching data can be removably set in the data inputting means 154 of the processing means 150. The teaching data in the storage device are transmitted to the memory for teaching data 152. The servo unit 160 replays the operation of the robot body 110 following the teaching data stored in the storage device, when the choosing switch 140 is set for the replaying operation mode.
As shown in FIGS. 10 to 12, the robot control unit 120 and the teach-inputting means 130 are disposed near the robot body 110, that is, near the real-operating site. Thus, at a remote place, the teaching data can not be made while the operator confirms the movement of the robot body 110, when the robot body 110 actually moves.
The teaching data stored in the storage device which can be set in the data inputting means 154 are made at a remote place. However, the teaching data are not made while the operator confirms the movement of the robot body 110 when the robot body 110 actually moves. Thus, the teaching data stored in the storage device may include a wrong teaching data which may bring a risk.
Thus, according to the prior art, the teach-inputting operation has to be executed near the robot body 110 when the operator wants to confirm the movement of the robot body 110 during the teach-inputting operation. The real-operating site where the robot body 110 is disposed, for example a factory, may be environmentally polluted by a welding operation or the like, and may be dangerous for the operator. Thus, safety measures for the operator are not assured.
FIG. 13 is a schematic perspective view showing a structure of another prior art. In the structure, the electric signal line 111 is relatively long, so that the robot control means 120 is disposed at a safer place, which is away from the real-operating site where the robot body 110 is disposed. The robot control means 120 is connected to the teach-inputting means 157 which can be materialized by a personal computer, through the electric signal line 156.
The robot body 110 and the robot control means 120 are constituted in the same manner as shown in FIGS. 10 to 12. The processing circuit 151 in the processing means 150 is connected to the personal computer 157 through the line 156. The personal computer 157 has a key-input means and a liquid crystal panel for showing teaching data inputted by the key-input means. The structure is not provided with means similar to teach-inputting means 130 of the previous prior art.
In the case of the prior art shown in FIG. 13, the personal computer 157 for inputting the teaching data can be disposed at a place away from the real-operating site where the robot body 110 is disposed. Thus, the safety for the operator is assured. Then, the operator can watch the replaying robot body 110 at the safer place.
A disadvantage of the prior art shown in FIG. 13 is that the robot body 110 does not actually move following the teaching data when the teaching data are inputted via the personal computer 157. The operator transmits the teaching data made by the personal computer 157 into the memory for teaching data 152 provided in the processing means 150 of the robot control means 120 through the electric signal line 156. The servo unit 160 replays the moving operation for the robot body 110, following the teaching data stored in the memory for teaching data 152. Thus, the operator tends to make an error in inputting the teaching data.
In addition, according to the prior art shown in FIG. 13, the electric signal line 111 connecting the robot body 110 with the robot control means 120 can not be more than 20 meters because of electrical resistance thereof.